Participation of the beta-ketoadipate transport system in chemotaxis

beta-Ketoadipate serves as a chemoattractant for Pseudomonas putida. The chemotactic response is inducible, and a regulatory mutant strain that forms the beta-ketoadipate transport system at high levels exhibits a heightened chemotactic response to beta-ketoadipate. Adipate and succinate, compounds that interact with the transport system, inhibit chemotaxis toward beta-ketoadipate. Some, but not all, mutants that fail to respond chemotactically to beta-ketoadipate lack the beta-ketoadipate transport system. It thus appears that the transport of beta-ketoadipate is associated with its function as a chemoattractant. It is likely that the metabolite attracts fluorescent Pseudomonas species to environments in which complex aromatic polymers undergo microbial dissimilation.